Application of Divertor Pumping to Long-Pulse Discharge for Particle Control in LHD

Gen MOTOJIMA, Suguru MASUZAKI, Tomohiro MORISAKI, Masahiro KOBAYASHI, Ryuichi SAKAMOTO, Yasuyuki TSUCHIBUSHI, Takanori MURASE, Yasuhiko TAKEIRI, the LHD experiment group
2021 Plasma and Fusion Research  
Divertor pumping was applied to plasma discharges for superior fuel particle control in the Large Helical Device (LHD). The LHD is equipped with two different pumping systems. One is the main pumping system, in which the pumping speed is 260 m 3 /s in hydrogen. The other pumping system is the divertor pumping system in which the pumping speed is 70 m 3 /s in hydrogen. Divertor pumping was applied to 40-second long pulse Electron Cyclotron Heating (ECH) discharges to assess the improvement in
more » ... e improvement in particle control provided by divertor pumping. The results show that without divertor pumping, the electron density was not controlled by gas puffing using the feedback signal of line-averaged electron density. Then, the plasma confinement deteriorated, finally leading to radiation collapse. On the other hand, with divertor pumping, the density was well-controlled by gas puffing using the feedback signal. The results indicate that divertor pumping is one of the key tools for controlling the particles in fusion plasmas.
doi:10.1585/pfr.16.1202014 fatcat:rkxed4ky5jejnkrilcvijlzema